Olefin polymerization catalysts are of great use in industry. Hence there is interest in finding new catalyst systems that increase the commercial usefulness of the catalyst and allow the production of polymers having improved properties.
WO2011/158241 is generally directed to the use of homogeneous catalytic systems which include a pre-catalyst complex of a Group IV metal and a salalen ligand in the polymerization of alpha-olefins. The alpha-olefin polymers obtained are characterized by controlled levels of tacticity. Also disclosed are salalen ligands and complexes thereof with Group IV metals.
EP1849778, EP2003135, JP2007284438, Berkessel et al. “A Practical and Versatile Access to Dihydrosalen (Salalen) Ligands: Highly Enantioselective Titanium In Situ Catalysts for Asymmetric Epoxidation with Aqueous Hydrogen Peroxide, Adv. Syn-Cat. 2007, 349, 2385-2391, and Nakano et al. “Alternating Copolymerization of Cyclohexene Oxide with Carbon Dioxide Catalyzed by (salalen)CrCl Complexes”, Macromolecules 2009, 42, 6972-6980 are generally directed to methods and uses of various Group 4-6 salalen transition metal compounds as catalysts for various materials and processes.
Whitelaw et al. “Group 4 Salalen Complexes and Their Application for the Ring-Opening Polymerization of rac-Lactide” Inorg. Chem., 2010, 49 (15), pp 7176-7181 is generally directed to group 4 salalen complexes suitable to polymerize lactic acid to produce rac-lactide and isotactic polylactic acid both in the melt and in solution.
A. Yeori, et al. “Salalen: a hybrid Salan/Salen tetradentate AONNOU type ligand and its coordination behavior with group IV metals” Inorg. Chem. Commun. 2004, 7, 280-282; and Tshuva et al. “Isospecific living polymerization of 1-hexene by a readily available nonmetallocene 02-symmetrical zirconium catalyst, J. Am. Chem. Soc. 2000, 122, 10706-10707 are generally directed to catalysts for polymerization of alpha olefins.
Press et al. “Salalen Titanium Complexes in the Highly Isospecific Polymerization of 1-Hexene and Propylene” Angew. Chem. Int. Ed. 2011, 50, 3529-3532 is generally directed to salalen catalysts capable of forming isotactic polypropylene; and Press et al. “Zirconium and hafnium Salalen complexes in isospecific polymerisation of propylene”, Dalton Trans., 2013, 42, 9096 is generally directed to dibenzylzirconium and dibenzylhafnium Salalen complexes in polymerization of propylene with MAO as a cocatalyst.
Other references of interest include U. Zucchini et al. J. Organomet. Chem. 1971, 26, 357-372; Bryliakov et al., Eur. J. Org. Chem. 2008, 3369-3376; Gendler et al., J. Am. Chem. Soc. 2008, 130, 2144-2145; Cohen et al. Macromolecules 2010, 43, 1689-1691, and Altomare et al., J. Appl. Cryst., 1993, 26, 343-350. All the above listed references are incorporated by reference herein.
Accordingly, there is a need in the art for new and improved catalysts and catalyst systems to obtain new and improved polyolefins, polymerization processes, and the like. Accordingly, there is a need in the art for new and improved catalyst systems for the polymerization of olefins, to achieve specific polymer properties such as high tacticity, high molecular weight or a combination thereof.